The invention relates to an axial bearing for a banding roll of a banding machine with a shaft which is rigidly attached to a machine frame or chassis, and a rear cover plate which is also rigidly attached, a hub which is freely rotatable on the shaft and a flange which is arranged on the free face of the shaft with a front cover plate.
In banding machines, a strip-like film of paper, plastic or a composite is guided in a band guide, limiting the extension, as a loop about a stack of packaged products. This band guide is formed as an open or closed loop depending on the rigidity of the banding, the dimensions and use of the banded stack of packed product.
Basically, the goods to be packaged and to be banded can be configured in any manner, for example square, rectangular, round or trapezoidal with regard to area. At least one banding roll is positioned, simultaneously or successively in the case of several.
A fully automatic banding machine first forms an inherently stable or raised loop in which is placed the stack of packed products. The stack of packed products can be inserted before the loop is formed, sensor-controlled or triggered by hand or foot switch, the package band which is firmly clamped at its free end is retracted until it lies firmly against the packed products. Then the clamped end is glued or welded to the package band and cut.
The basic principle of banding is known on a broad basis. EP 0551244 A1 describes a banding machine which comprises cold welding. This refinement ensures a clean closure, requires little maintenance, and prevents deposits of burnt film and the replacement of heating elements.
Although at present banding rolls provide up to around 800 m of paper or even 1300 m of film, they must be changed relatively frequently during continuous operation. In non-specialised operations small banding rolls are used and replaced as required. A roll change must therefore be as simple as possible with relation to clamping of the roll and threading of the band.
Conventional band widths for package band are 15, 20, 30, 40, 50, 60, 75 and 100 mm. Compared to the width, the diameter is large to very large, so to avoid lateral offsets cover plates are arranged on both sides which do not rotate during unrolling.
Banding rolls have a roll core of cardboard which is pushed onto the freely rotating hubs. Due to unavoidable production tolerances the banding rolls are occasionally pushed on insufficiently, where roll-wound package band that is laterally offset grinds on a cover plate, a braking effect occurs causing the band tightening motor to be overloaded. Operating interruptions that are time-consuming and have a negative effect on production costs should be avoided as a precaution.
The invention is based on the object of creating an axial bearing of the type cited initially which allows a simpler roll change and fault-free operation as far as possible.